Given the SqlAlchemy models where I defined a FK relation between business_partner_table and users_table

user_table = sqlalchemy.Table(
    "users",
    metadata,
    sqlalchemy.Column("id", sqlalchemy.Integer, primary_key=True),
    sqlalchemy.Column("first_name", sqlalchemy.String),
    sqlalchemy.Column("last_name", sqlalchemy.String),
    sqlalchemy.Column("email", sqlalchemy.String, unique=True),
)

and

business_partner_table = sqlalchemy.Table(
    "business_partners",
    metadata,
    sqlalchemy.Column("id", sqlalchemy.Integer, autoincrement=True, primary_key=True, nullable=False),
    sqlalchemy.Column("card_name", sqlalchemy.String),
    sqlalchemy.Column("created_by", sqlalchemy.ForeignKey("users.id")),
)

I am struggling to implement SQLAlchemy ORM relationship in a non_declarative way
Below this is what i try to do:

@mapper_registry.mapped
class User:
    __table__ = user_table
    business_partners = relationship("BusinessPartner", back_populates="created_by_user")

@mapper_registry.mapped
class BusinessPartner:
    __table__ = business_partner_table
    created_by_user = relationship(
        "User",
        foreign_keys=[business_partner_table.c.created_by],
        back_populates="business_partners"
    )

API request looks as follow but I’m getting an error.

async def get_business_partners(current_user: Annotated[User, Depends(get_current_user)]):
    
    query = (select(business_partner_table)
             .where(business_partner_table.c.deleted_by == null())
             .options(joinedload(BusinessPartner.created_by_user))
             .order_by(business_partner_table.c.card_code))

My goal is to return the Business Partner in which the user data is nested within the created_by field.